The present invention relates to traffic control devices, in particular, to an attachment to a traffic light apparatus for visual indication of traffic light duration.
It has been known heretofore to incorporate into a traffic light various means for indicating the time left for illumination of a traffic light signal of one color before switching to a traffic light signal of another color.
For example, U.S. Pat. No. 4,255,737 issued in 1981 to R. Casteel teaches a traffic light apparatus, that has a four-sided housing, each side of which contains red and green areas that can be illuminated. Furthermore, each side contains a rotating semicircular mask which simultaneously and progressively covers one portion of one of the colored areas and uncovers a portion of the other colored area until the illumination of the traffic light is changed, thereby causing a change in traffic flow. The rotation of the masks together with the actuation of the various lights is controlled from a common ring gear disposed within the housing and driven by a single motor. A disadvantage of this device is that it incorporates the traffic light covering/uncovering means directly into the traffic light apparatus. In other words, for introducing such a device into practice, it would be required to replace all existing conventional traffic lights, which is not only expensive but may increase the occurrence of accidents because of confusion caused by new appearance of the traffic lights. Another disadvantage of the aforementioned traffic light apparatus is that it has a complicated mechanical construction with a plurality of interconnected moving parts. These parts operate synchronously and simultaneously in four opposite directions. Traffic light apparatuses of this type have to be suspended from a console or another type support above the center of the intersection. However, in a majority of cases, traffic lights of such type have been replaced by apparatuses installed on the corners of the street crossings and having signals facing only the oncoming traffic. Therefore the aforementioned device of U.S. Pat. No. 4,255,737 may find only an extremely limited practical application. Furthermore, this apparatus is not applicable to intersections, which require different traffic signals for vehicles going in mutually opposite directions, e.g., a red light in one direction and a left turn/green light for the vehicle going in the opposite direction. It would be very difficult to adjust and change the mode of operation in the above-described apparatus.
U.S. Pat. No. 4,590,455 issued in 1986 to G. Fritzinger teaches a traffic control system that has green and/or red signal lights blinked momentarily at a predetermined interval before the direction of traffic is changed. A marker is placed along the roadway at a normal distance of travel within the timing of the blink signal to enable motorists to gauge their driving to save gasoline and achieve greater safety solely by noting their location relative to the marker when the blink signal occurs. Further taught is the use of the traffic signaling system in connection with a semi-actuated controller that has a synchronizer providing a background cycle. The timing of the blink signal and the yellow caution signal is obtained from the synchronizer. A disadvantage of this device is that blinking of the green signal may cause confusion, whereas blinking of the red signal is already equivalent to a stop signal and may not be understood as an indicator of the approaching switch in the traffic direction. Furthermore, an addition of a marker on the road at the approach to the traffic light may distract the driver""s attention.
U.S. Pat. No. 5,726,648 issued in 1998 to M. Soon describes a time indicating traffic light that includes a vertically-oriented and rectangular-parallelepiped-shaped housing, a circular-shaped xe2x80x9cstopxe2x80x9d indicator light, a circular-shaped xe2x80x9ccautionxe2x80x9d indicator light, seven rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights, and a time indicating display. The circular-shaped xe2x80x9cstopxe2x80x9d indicator light, the circular-shaped xe2x80x9ccautionxe2x80x9d indicator light, and the seven rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights are disposed in the vertically-oriented and rectangular-parallelepiped-shaped housing. The seven rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights have a pair of parallel, elongated, spaced-apart, vertically-oriented, and rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights, and five adjacent, slightly vertically spaced-apart, horizontally-oriented, and rectangular-shaped xe2x80x9cgoxe2x80x9d lights. The five adjacent, slightly vertically spaced-apart, horizontally-oriented, and rectangular-shaped xe2x80x9cgoxe2x80x9d lights extinguish progressively upwardly towards the circular-shaped xe2x80x9ccautionxe2x80x9d indicator light at a predetermined rate determined by a timer while the pair of parallel, elongated, spaced-apart, vertically-oriented, and rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights remain illuminated when at least one light of the five adjacent, slightly vertically spaced-apart, horizontally-oriented, and rectangular-shaped xe2x80x9cgoxe2x80x9d lights is illuminated. The time indicating display is disposed on the vertically-oriented and rectangular-parallelepiped-shaped housing and provides a visible display of the time of illumination of the seven rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights, so that an approaching vehicle can determine when the circular-shaped xe2x80x9ccautionxe2x80x9d indicator light will be illuminated by dividing the time of illumination on the time indicating display by the number of lights of the five adjacent, slightly vertically spaced-apart, horizontally-oriented, and rectangular-shaped xe2x80x9cgoxe2x80x9d lights extinguished and thereby prevent sudden acceleration followed by a sudden stop.
A disadvantage of this time-indicating traffic light consists in that it is based on an entirely new conception and would require replacement of all existing traffic light units. Another disadvantage is that the device has a rather complicated construction, and therefore is expensive to manufacture. A provision of several different rectangular-shaped xe2x80x9cgoxe2x80x9d indicator lights would require an essential increase in the overall dimensions of the traffic light assembly, as it would be necessary to make each xe2x80x9cgoxe2x80x9d indicator light and the digital indicator visible from a far distance. A driver may need time for obtaining, processing the information indicated by the complicated traffic light system, and for making a decision. All this has to be done immediately, which may not be feasible for an elderly people whose driving ability would be limited.
U.S. Pat. No. 6,087,962 issued in July 2000 to Hector R. Rojas describes an electric traffic light, with acoustic signs and with an indication of backward counting which includes lights prepared in three sectors with signaling screens that are controlled by a processor electrically linked to an optic and numeric counter. The circuit of optic formation is programmed in sequence and time to emit activation signals to certain sections of the lights to provide the brightness of the light on each screen. The circuit of the numeric formation is programmed to send signals of interruption of the power supply, simultaneously with the optic circuit, to certain sectors of the lights to provide visualization of numbers. Further, simultaneously with the optic and numeric circuit, a sound emitter emits a sound with each color.
A disadvantage of the device of U.S. Pat. No. 6,087,962 is that it has a complicated construction, requires modernization of all existing traffic lights, and that the numbers displayed on the color screens are not very legible from a distance and have dimensions limited by the diameters of the color screens, which are not very large.
The applicant of the present patent application has invented an attachment to a traffic light apparatus for visual indication of traffic light duration, which is disclosed in pending U.S. patent application Ser. No. 09/300,875 filed on Apr. 28, 1999 and for which a notice of allowance has been received.
The device of U.S. patent application Ser. No. 09/300,875 comprises an attachment to a conventional traffic light and is connected to its side wall for visually indicating the duration of the time remaining till switching of the current green, yellow, or red light in proportion to the dimension of the illuminated portion of the indicator. In accordance with one embodiment, the device is made in the form of a housing with a rotating drum, which is divided into three sections by nontransparent partitions, each containing an individual lamp. The cylindrical surface, which defines the periphery of each section of the drum, has a transparent portion in the form of a wedge. When the drum rotates, the lit sector is shown in the window of the device so that during rotation of the drum, the dimensions of the lit portion of the drum shown through the window decrease proportionally to the remaining part of the current traffic light signal. A disadvantage of the apparatus of this embodiment is a complicated construction, which contains rotating parts.
In accordance with another embodiment of the above application, the device for visual indication of traffic light duration consists of four panels arranged in a cross-like configuration with traffic lights placed into corner of each quadrants formed by the panels, so that a respective traffic light is seen from each direction of movement of vehicles. Each panel, in turn, consists of three sectors, each for respective color of the traffic light. Each sector is formed by several tubular fluorescent lamps connected in parallel to a source of electric power supply, so that under control of the CPU, controller, and relay, each sector indicates the time remaining to the moment of switching of the traffic light to another color by switching of fluorescent lamps in a stepwise manner. Only a sector, which is associated with the currently lit traffic light, operates one at a time, while the next sector is activated only with the activation of the next traffic light. Thus, in the device of the last-mentioned embodiment, the width of the warning panel is limited to the height of the traffic light apparatus, and only one of three sectors operates at a time. In other words, the overall dimensions of the warning sign device are limited and the entire warning indication panel is used inefficiently, as only about 30% of the panel surface is used at each moment of time. Thus, the lit cell cannot be seen well during rain, fog, or at other bad-weather conditions. Another disadvantage of the device under consideration is that its location is bound to the traffic light apparatus, as each panel is additionally is used as a shade for the traffic light.
It is an object of the invention to provide an attachment to traffic light apparatus for visual indication of traffic light duration, which is simple in construction, is free of moving parts, ensures sequential indication of traffic light duration signs of different colors over the entire length of the indication panel and therefore may have large dimensions, and can be installed in any convenient location, irrespective of the position of the traffic light apparatus.